Resilient crystal for clocks and like instruments



t. l 2 l 646 841 0c 9 7 R. H. WHITEHEAD ET AL HESILIENT CRYSTAL FQRCLOCKS AND LIKE' INSTRUMENTS Filed Nov. 9, 1926 vided with yieldingcrystals of celluloid or Patented oer. 25, 1927'.

' UNITED STATES PATENT OFFICE.

BICI IABD' H. WHITEHEAD AND WILSON E. PORTER, OF ,NEW HAVEN,CONNECTICUT,

: ASBIGNOBS TOTHE NEW HAVEN CLOCK 00., OF NEW HAVEN, CONNECTICUT, A COR-PORLTION.

v BESILIENT CRYSTAL FOR CLOCKS AND LIKE INSTRUMENTS.

Application fl'led November 9, 1926. Serial No. 147,255.

Our invention relates to an improvement in-that class of small portableclocks proequivalent, non-breakable, transparent material, in place ofrigid crystals of glass, the object being to produce, at a low cost formanufacture, a high-grade and attractive clock having the advantagesincident to the use of a non-breakable crystal, together with somemanufacturing'advantages to hereinafter appear.

With these ends in view, our invention consists in a resilient crystalhaving its actual edges initially bowed out of a common plane so thatwhen such edges are placed under tension from their opposite faces, theywill be brought substantially into a common plane, whereby the case-unitand the movement-unit of the clock in which the said crystal is placedwill be stabilized in their relative positions by the effort of the saidbowed edges of the crystal to resume their initially-bowed form.

In the accompanying drawings:

Fig. 1 is a View in vertical central 'section ofone form which acelluloid-crystal clock embodying our invention may assume;

Fig. 2 is a corresponding view thereof before the crystal has beenplaced under ten- S1011 Fi 3 is a detached plan view of the crystal ater it has been bowed;

Fig. 4 is an edge view thereof; and

Fig. 5 is an end view thereof.

In carrying out our invention, as herein shown, we employ an oblong,rectangular,

. convex, yielding crystal 10 of celluloid or any other equivalent,nonbreakable, transparent material having its actual side-edges 11 andits actual end-edges 12 initially bowed in line parallel therewith, asshown particularly in Figs. 4 and 5. In other words, under my invention,the bowing of the edges is concerned with the thickness thereof and runsparallel therewith, as distinguished from crimping or heading the bodyof the crystal, within its ultimate edges in lines transverse thereto.

This crystal is adapted in length and width to fit within aretaining-flange 13 produced by turning inwardly thefforward edge of anoblong, rectangular, sheet-metal case 14 receiving a marine movement ofany approved 7 standard construction and generallydesignated by thenumeral 15. The said movement 15 has secured to it an oblong rectangulardial-plate 16 and a corresponding back-plate 17, the movement and platesforming the movement-unit of our improved clock. The twoplates 16 and17are adapted in size to snugly fit within the case 14, so, that, when themovement-unit is inserted into the case 14 from the rear thereof, thesideand end-edges of the dial-plate 16 will engage with the rear facesof the corresponding initially-bowed edges of the yielding, nonbreakablecrystal 10 aforesaid.

' The said movement-unit is held in place by means of retaining-blocks18, held in engagement with the rear face of the end-edges of theback-plate 17 by screws 19 passing transversely through the case 14,which, withthe said blocks and screws, forms the case-unit of ourimproved clock.

The parts described are so proportioned thatwhen the movement-unit isproperly positioned within the case-unit, the opposite faces of theinitially-bowed-edges 1111 and 12-12 of the convex, celluloid crystal 10will be so firmly clamped between the retainingfiange 13 of the case 14and the sideand endedges of the dial-plate 16, that they will bemeasurably straightened out and form an effective yielding joint of acompensatory character, so that any inequalities in the thickness orbowing of the crystal, or varia-- tions in the positioning of themovementunitin the case-unit will be compensated for, making the clockconvenient to assemble and independent of exacting accuracy of construction. The rattling of the crystal, common to clocks having glasscrystals, is also entirely eliminated, and also any rattling of themovement-unit in the case-unit.

Furthermore, the breakage of the crystal,

due to blows which would ordinarily result edges initially. bowed out ofa common plane, I

so that when such edges are placed under tension from their oppositefaces, they will be brought substantially into a common plane, wherebythe case-unit and the movement-unit of the clock in which the saidcrystal is placed will be stabilized in their relative positions by .theeffeort of the said bowed edges of the crystal to resume theirinitially-bowed form.

2. A resilient polygonal crystal having its actual edges'initially bowedout of a common lane in a direction arallel with the said e ges, 'sothatwhen suc edges are placed under tension from their 0 posite faces, theywill be brought substantia ly in'toa common plane, where y the case-unitand the 'movement-unit of the clock in which the said or stal is placedwill be stabilized in their re a.

